Connections of the second auditory cortical area with the medial geniculate body and the first auditory area

Extra — and intracellular unit responses in area AII to stimulation of geniculocortical fibers and of area AI were studied in cat immobilized with D-tubocurarine. In response to stimulation of geniculocortical fibers, antidromic mono-, di-, and polysynaptic spikes were generated by neurons in area AII. The number of antidromic responses in area AII was about half that found in area AI under the same conditions of stimulation. Most of the orthodromic responses were di- and polysynaptic. Intracellular responses also were recorded in the form of EPSPs, EPSP-IPSPs, and primary IPSPs. Stimulation of area AI evoked responses in the neurons of area AII with latent periods of 0.75–6.0, 6.1–16.0, 18.0–23.0, and 60–100 msec. Removal of the medial geniculate body led to a marked decrease in the number of responses with latent periods of 6.1–16.0 msec. Some neurons of area AII responded by spikes to stimulation of both the geniculocortical fibers and area AI. Comparison of the latent periods of responses to these two types of stimulation showed that impulses from area AI to area AII are directed both to input neurons for impulses from the medial geniculate body and to neurons at subsequent stages of the intracortical neuronal change. In response to stimulation of cortical area AI, disynaptic IPSPs appeared in many neurons of area AII. Only one IPSP with a latent period of 1.0 msec, regardable as monosynaptic, was recorded.     

Characteristics of cortical inhibitory neurons

Spikes were recorded extracellularly and IPSPs intracellularly from auditory cortical neurons of cats immobilized with D-tubocurarine in response to stimulation of geniculo-cortical fibers. Fibers whose stimulation induces IPSPs in auditory cortical neurons mainly have low thresholds. When two stimuli, each of which separately evoked an IPSP of maximal amplitude, were applied to them the shortest interval at which the second stimulus evoked an effect was 2.5–3 msec. This effect consisted of an increase in the duration of the integral IPSP, the amplitude of which either remained unchanged or increased under these circumstances by only 5–10%. The interval at which a separate IPSP appeared in response to the second stimulus depended on the duration of the ascending phase of the IPSP and varied from 4 to 22 msec for different neurons. The amplitude of the second IPSP in this case depended on the interval between stimuli. Under moderately deep pentobarbital anesthesia the number of neurons responding to stimulation of the geniculo-cortical fibers by spikes fell sharply but the number of neurons responding by primary IPSPs remained almost unchanged. Under very deep pentobarbital anesthesia, when spike responses of the cortical neurons completely disappeared, the IPSPs also were completely suppressed. It is concluded that inhibitory neurons of the auditory cortex are excited by thick low-threshold fibers, they have a short refractory period, and they are resistant to the narcotic action of pentobarbital.     

Unit responses of the second auditory area to acoustic stimulation

Responses of 116 neurons of the second auditory area to clicks were recorded extracellularly in experiments on unanesthetized cats immobilized with D-tubocurarine. Neurons with and without (54.6%) took part in the response to clicks. The unit response to a click consisted of 1 or 2 spikes or a short volley. Different neurons responded to clicks at different times. The latent period of 25.8% of all neurons recorded was 6.5–13 msec, of 70% it was 14–25 msec, and of 4.2% it was over 25 msec. Long-latency responses to clicks (40, 50, and 100 msec) also were recorded. The responding neurons were found throughout the thickness of the cortex, but more frequently in layers III and IV. No relationship was found between the depth of the neuron and its latest period. Responses consisting of EPSP, EPSP-spike, EPSP-spike-IPSP, EPSP-IPSP, and primary IPSP were recorded intracellularly from the neurons of this area. It was concluded from the results that neurons of the second auditory area can be activated by the arrival of an afferent volley along the geniculo-cortical pathway and also by the arrival of impulses from the first auditory area.     

Modulation,Bioinformatic Screening,and Assessment of Small Molecular Peptides Targeting the Vascular Endothelial Growth Factor Receptor

Vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) are important factors in tumor growth and metastasis. Molecular probes or drugs designed to target VEGF/VEGFR interactions are crucial in tumor molecular imaging and targeted therapy. Bioinformatic methods enable molecular design based on the structure of bio-macromolecules and their interactions. This study was aimed to identify tumor-targeting small-molecule peptides with high affinity for VEGFR using bioinformatics screening. The VEGFR extracellular immunoglobulin-like modules Ig1–Ig3 were used as the target to systematically alter the primary peptide sequence of VEGF_125–136. Molecular docking and surface functional group interaction methods were combined in an in silico screen for polypeptides, which in theory, would have higher affinities for VEGFR. In vitro receptor competition binding assays were used to assess the affinity of the putative VEGFR-binding polypeptides. Rhodamine-conjugated peptides were used to label and visualize peptide-binding sites on A549 cells. Using bioinformatic screening, we identified 20 polypeptides with potentially higher affinity for VEGFR. The polypeptides were capable of inhibiting the binding of ¹²⁵I-VEGF to VEGFR in a dose-dependent manner. The IC₅₀ values of QKRKRKKSRKKH and RKRKRKKSRYIVLS (80 and 185 nmol/L, respectively) were significantly lower than that of VEGF_125–136 (464 nmol/L); thus, the affinity of these peptides for VEGFR was 6- and 2.5-fold higher, respectively, than that of VEGF_125–136. Rhodamine labeling of A549 cells revealed peptide binding mainly on the plasma membrane and in the cytoplasm. Bioinformatic approaches hold promise for the development of molecular imaging probes. Using this approach, we designed two peptides that showed higher affinity toward VEGFR. These polypeptides may be used as molecular probes or drugs targeting VEGFR, which can be utilized in molecular imaging and targeted therapy of certain tumors.     

Inhibition in the olfactory bulb of the lizard

Inhibition in neurons of the lizard olfactory bulb was investigated by intracellular recording. The hyperpolarization arising in the neurons after the spike in the response to orthodromic and antidromic activation is similar in composition and reflects the development of early and late IPSPs, differing from one another in latency, duration, and mechanism of generation. The early IPSP is evidently generated by the functioning of dendrodendritic synapses, formed by dendrites of the interglomerular cell on the membrane of the apical dendrites of the secondary neurons, whereas synapses generating the late IPSP are located on the basal dendrites and are formed by endings of the granular cells. The mechanisms of generation of the early and late IPSPs in the secondary neurons are discussed. A classification of neurons of the lizard olfactory bulb is given on the basis of analysis of their intracellular activity.     

Spontaneous activity and evoked responses of cerebellar cortical neurons to vagal and limb nerve stimulation in pigeons

Spontaneous activity and evoked reponses of the cerebellar cortical neurons of decerebrate pigeons to stimulation of the vagus nerve and nerves of the limbs were investigated. The cell responses were uniform in type regardless of the character of stimulation. Phasic and tonic responses, predominantly of excitatory type, were recorded. The phasic responses had both short (10–20 msec) and long (up to 80 msec) latent periods. The latter predominated. Features distinguishing the unit responses to vagal stimulation of the limb nerves included: a smaller number of activated cells, longer latent period of the responses, absence of activation of Purkinje cells through the climbing fibers, and lower capacity for rhythm binding.     

Polymorphism of DNA Repair Gene xrcc1 and Lung Cancer Risk

The current large-scale meta-analysis was performed to reach a reliable conclusion on the association between X-ray repair cross-complementing 1 (xrcc1) rs1799782 and the development of lung cancer. Studies that investigated the association between rs1799782 and lung cancer risk were identified by searching PubMed. We calculated odds ratio (OR) with corresponding 95 % confidence interval (CI) for Trp/Trp vs Arg/Arg, Trp/Trp + Arg/Trp vs Arg/Arg, and Trp/Trp vs Arg/Trp + Arg/Arg contrast models. Combining all 25 studies, we yielded three summary ORs: 1.07 (95 % CI 0.92–1.23) for Trp/Trp vs Arg/Arg, 0.93 (95 % CI 0.87–1.00) for Trp/Trp + Arg/Trp vs Arg/Arg, and 1.08 (95 % CI 0.94–1.25) for Trp/Trp vs Arg/Trp + Arg/Arg, suggesting rs1799782 was not associated with overall risk of lung cancer. Strikingly, a significantly deceased risk was found among Caucasian populations (Trp/Trp + Arg/Trp vs Arg/Arg, OR = 0.86, 95 % CI 0.76–0.97). This study confirms that xrcc1 rs1799782 may lower the risk of lung cancer among Caucasians.     

Expression of microRNA-1, microRNA-133a and Hand2 protein in cultured embryonic rat cardiomyocytes

In this study, we investigated the expression of the pathway, SRF–microRNA-1/microRNA-133a–Hand2, in the Wistar rat embryonic ventricular cardiomyocytes under conventional monolayer culture. The morphological observation of the cultured cardiomyocytes and the mRNA expression levels of three vital constituent proteins, MLC-2v, N-cadherin, and connexin43, demonstrated the immaturity of these cultured cells, which was featured by less myofibril density, immature sarcomeric structure, and significantly lower mRNA expression of the three constituent proteins than those in neonatal ventricular samples. More importantly, results in this study suggest that the change of SRF–microRNA-1/microRNA-133a–Hand2 pathway results into the attenuation of the Hand2 repression in cultured cardiomyocytes. These outcomes are valuable to understand the cellular state as embryonic cardiomyocytes to be in vitro model and might be useful for the assessment of engineered cardiac tissue and cardiac differentiation of stem cells.     

MicroRNA-2 Suppresses Lewis Lung Cancer Cells Proliferation,Invasion, and Migration in Tumor-Bearing Mice

We sought to find the biological effects of MicroRNA-2 in suppressing Lewis lung cancer cells proliferation, invasion, and migration in tumor-bearing mice. MicroRNA-2 was transfected into Lewis lung cancer cells of tumor-bearing mice by gene transient transfection technique and these Lewis-microRNA-2 cells were taken as MicroRNA transfection group. At the same time, Lewis cells were taken as control group and Lewis-EGFP cells as empty plasmid group. The growth curves of cells in the three groups were drawn by manual counting method, while the invasiveness of cells in the three groups was compared by transmembrane cell invasion assay. The three kinds of cells were seeded into BALB/Nude SPF level nude mice to detect the formation of tumors and the number of metastases by Xenograft experiments. The result showed that the MicroRNA transfection group has the lowest vitality of cells proliferation, fewest cells passed through matrigel matrix protein layer, and lowest cells invasive rate. Mice with Lewis-microRNA-2 cells apparently had a longer time of tumor formation. The average tumor mass and the number of metastases were significantly lower than the other two groups. MicroRNA-2 significantly inhibited Lewis lung cancer cell proliferation, invasion and migration in tumor-bearing mice, which may be associated with the regulation of target genes PLK1 and TGF-β.     

Ribosomal RNA contents of maize genotypes with different ribosomal RNA gene numbers

Ribosomal RNA (rRNA) contents were determined in 16 maize genotypes whose individual rRNA gene numbers varied from 5000 to 23,000 per 2C nucleus. Analytical polyacrylamide gel electrophoresis of total RNA showed that no obvious relation existed between rRNA gene number and rRNA content. Only two of nine common inbred lines contained more rRNA than W-23, the inbred with the lowest rRNA gene number. Two of four lines with altered protein content (due to long-term experimental selection) had rRNA contents significantly reduced from those of W-23. A line with an apparent duplication of the nucleolus organizer region of chromosome 6 (called 2-NOR) was expected to possess an elevated quantity of rRNA because it possesses a larger nucleolus; however, we produced a 2-NOR isogenic version and found no difference in rRNA content. The rRNA genes in maize are distributed throughout the NOR-heterochromatin and the NOR-secondary constriction portions of the NOR. The absence of an obvious correlation between rRNA gene number and cellular rRNA content may reflect the presence of a large number of rRNA genes in an inactive state, at least during the stage of growth examined in these experiments.     

Apparent Reduction of ADAM10 in Scrapie-Infected Cultured Cells and in the Brains of Scrapie-Infected Rodents

It has been described that A disintegrin and metalloproteinase (ADAM10) may involve in the physiopathology of prion diseases, but the direct molecular basis still remains unsolved. In this study, we confirmed that ADAM10 was able to cleave recombinant human prion protein in vitro. Using immunoprecipitation tests (IP) and immunofluorescent assays (IFA), reliable molecular interaction between the native cellular form of PrP (PrP^C) and ADAM10 was observed not only in various cultured neuronal cell lines but also in brain homogenates of healthy hamsters and mice. Only mature ADAM10 (after removal of its prodomain) molecules showed the binding activity with the native PrP^C. Remarkably more prion protein (PrP)-ADAM10 complexes were detected in the membrane fraction of cultured cells. In the scrapie-infected SMB cell model, the endogenous ADAM10 levels, especially the mature ADAM10, were significantly decreased in the fraction of cell membrane. IP and IFA tests of prion-infected SMB-S15 cells confirmed no detectable PrP-ADAM10 complex in the cellular lysates and PrP-ADAM10 co-localization on the cell surface. Furthermore, we demonstrated that the levels of ADAM10 in the brain homogenates of scrapie agent 263K-infected hamsters and agent ME7-infected mice were also almost diminished at the terminal stage, showing time-dependent decreases during the incubation period. Our data here provide the solid molecular basis for the endoproteolysis of ADAM10 on PrP molecules and interaction between ADAM10 and PrP^C. Obvious loss of ADAM10 during prion infection in vitro and in vivo highlights that ADAM10 may play essential pathophysiological roles in prion replication and accumulation.     

A Systems Biology Approach to Study the Biology Characteristics of Esophageal Squamous Cell Carcinoma by Integrating microRNA and Messenger RNA Expression Profiling

Esophageal squamous cell carcinoma (ESCC) is one of the most malignant tumors. The aim of this study was to investigate the biology characteristics of ESCC by analyzing microRNA and mRNA expression profile. We used BRB-array tools to analyze the deregulated microRNA and mRNA between esophageal squamous cell carcinomas and paired normal adjacent tissues. We used miRTrail and protein–protein interaction methods to explore the related pathways and networks of deregulated microRNA and mRNA. By combining the results of pathways and networks, we found that the deregulated microRNA and their deregulated target mRNA are enriched in the following pathways: DNA replication, cell cycle, ECM-receptor interaction, focal adhesion, mismatch repair, and pathways in cancer. The results showed that many deregulated microRNAs and mRNAs may play a vital role in the pathogenesis of ESCC, and the systems biology approach is very helpful to explore molecular mechanism of ESCC.     

Impregnation of the Bacterial Cellulose Membrane with Biologically Produced Silver Nanoparticles

Different wound dressings with antibacterial property have been surveyed and one among them is bacterial cellulose (BC). Since the BC does not have antibacterial property, the biologically produced silver nanoparticles (SNPs) were impregnated into the BC. For the BC production, Hestrin–Schramm broth was used. Formation of the BC was proven by enzymatic hydrolysis. For SNPs production, the bacterial supernatant was treated with AgNO₃ and formation of SNPs was monitored through spectrophotometer, TEM and XRD. For impregnation of SNPs into the BC, the cleaned membrane was placed in the bacterial supernatant that contained 1 mmol of AgNO₃. The antibacterial assay was done for the BC/SNPs. Enzymatic hydrolysis proved the presence of the BC. Spectrophotometer and XRD results showed the formation of SNPs. TEM analysis revealed the presence of SNPs with sizes around 5–100 nm. SEM micrographs showed the impregnation of SNPs into the BC. Antibacterial test exhibited the antibacterial activity of the BC/SNPs.     

Identification of nucleolus-localized PTEN and its function in regulating ribosome biogenesis

The tumor suppressor PTEN is a lipid phosphatase that is found mutated in different types of human cancers. PTEN suppresses cell proliferation by inhibiting the PI3K-Akt signaling pathway at the cell membrane. However, PTEN is also demonstrated to localize in the cell nucleus where it exhibits tumor suppressive activity via a different, unknown mechanism. In this study we report that PTEN also localizes to the nucleolus and that nucleolar PTEN plays an important role in regulating nucleolar homeostasis and maintaining nucleolar morphology. Overexpression of nuclear PTEN in PTEN null cells inhibits Akt phosphorylation and reduces cell size. Knockdown of PTEN in PTEN positive cells leads to nucleolar morphologic changes and an increase in the proportion of cells with a greater number of nucleoli. In addition, knockdown of PTEN in PTEN positive cells increased ribosome biogenesis. These findings expand current understanding of function and relevance of nuclear localized PTEN and provide a foundation for the development of novel therapies targeting PTEN.     

The investigation of the effect of pollination on ribosomal RNA,transfer RNA and DNA contents in styles ofNicotiana alata.

Using the phenol extraction method and MAK column chromatography the contents of nucleic acids in styles ofNicotiana alata were estimated before and up to 48 h after compatible pollination. As a result of pollination, high-molecular-weight rRNA and DNA registered a significant increase in their content approximating 30% and 16% respectively. The change in sRNA (4-S tRNA and 5-S rRNA) level was very slight and non-significant. In pollen grains there is an unusually high amount of rRNA with respect to the content of other nucleic acids and the rRNA/tRNA ratio approximates 14 : 1. On the other hand, in non-pollinated styles the content of rRNA is only about 6 times higher than that of tRNA. The changes in nucleic acid level found in styles after pollination are at least in a major part the result of the addition of the nucleic acids present in the amount of pollen used for pollination. The high rRNA level relatively to tRNA being generally associated with rapidly growing cells, its significance in pollen may be related to the rapid growth of pollen tubes.     

Quercetin Potentiates the Antitumor Activity of Rituximab in Diffuse Large B-Cell Lymphoma by Inhibiting STAT3 Pathway

STAT3 pathway plays an important role in the growth of diffuse large B-cell lymphoma (DLBCL) cells. Here we investigated the antitumor activity of Quercetin, a flavonoid compound, in combination with rituximab in DLBCL cell lines in vitro. We found that Quercetin synergistically enhanced rituximab-induced growth inhibition and apoptosis in DLBCL cell lines. Moreover, we found Quercetin exerted inhibitory activity against STAT3 pathway and downregulated the expression of survival genes. These results suggest that combining the Quercetin with rituximab may present an attractive and potentially effective way for the treatment of DLBCL.     

GABA Pharmacology: The Search for Analgesics

Decades of research have been devoted to defining the role of GABAergic transmission in nociceptive processing. Much of this work was performed using rigid, orthosteric GABA analogs created by Povl Krogsgaard-Larsen and his associates. A relationship between GABA and pain is suggested by the anatomical distribution of GABA receptors and the ability of some GABA agonists to alter nociceptive responsiveness. Outlined in this report are data supporting this proposition, with particular emphasis on the anatomical localization and function of GABA-containing neurons and the molecular and pharmacological properties of GABA_A and GABA_B receptor subtypes. Reference is made to changes in overall GABAergic tone, GABA receptor expression and activity as a function of the duration and intensity of a painful stimulus or exposure to GABAergic agents. Evidence is presented that the plasticity of this receptor system may be responsible for the variability in the antinociceptive effectiveness of compounds that influence GABA transmission. These findings demonstrate that at least some types of persistent pain are associated with a regionally selective decline in GABAergic tone, highlighting the need for agents that enhance GABA activity in the affected regions without compromising GABA function over the long-term. As subtype selective positive allosteric modulators may accomplish these goals, such compounds might represent a new class of analgesic drugs.